Rotterdam vs Almost Ideal Models: Will the Best Demand Specification Please Stand Up?

Among the many demand specifications in the literature, the Rotterdam model and the Almost Ideal Demand System (AIDS) have particularly long histories, have been highly developed, and are often applied in consumer demand systems modeling. Using Monte Carlo techniques, we seek to determine which model performs better in terms of its ability to recover the true elasticities of demand. We derive the correct formulae for the AIDS models elasticities, when the Törnqvist or two modified versions of the Stone index are used to linearize the model. The resulting linearized AIDS are compared to the full AIDS

Rotterdam vs Almost Ideal Models: Will the Best Demand Specification Please Stand Up?

Among the many demand specifications in the literature, the Rotterdam model and the Almost Ideal Demand System (AIDS) have particularly long histories, have been highly developed, and are often applied in consumer demand systems modeling. Using Monte Carlo techniques, we seek to determine which model performs better in terms of its ability to recover the true elasticities of demand. We derive the correct formulae for the AIDS models elasticities, when the Törnqvist or two modified versions of the Stone index are used to linearize the model. The resulting linearized AIDS are compared to the full AIDS.Rotterdam Model; Almost Ideal Model; consumer demand system; Monte Carlo study; flexible functional forms

Reproductive biology of the common torpedo, Torpedo torpedo (Linnaeus, 1758) (Pisces, Torpedinidae) from the coast of Senegal (Eastern Tropical Atlantic)

Among the five species of genus Torpedo recorded from the coast of Senegal, the common torpedo, Torpedo torpedo is that most cornrnonly caught in the area. Adult males and fernales studied were over 300 mm and 310 mm total length (TL), respectively, with the largest male and the largest female recorded being 445 mm and 550 mm TL respectively. Size at birth was between 102 and 125 mm TL (mean 112.12 mm; s.e.m. 5.58). Weight of eggs ranged frorn 6.2 to 8.0 g (rnean: 7.07; s.e.m. 0.5). Gestation lasts longer, from 6 to 8 rnonths, than in the Mediterranean specimens. A calculated chernical balance of development based on rnean dry weights of the fully developed fetuses and ripe oocytes was 1.58 for T. torpedo. This value shows that this torpedinid is not a pure lecithotrophic species, and the role of the rnother during gestation is not negligible. The fecundity (s.1.) of T. torpedo ranges from 5 to 28 in Senegalese specimens as cornpared to 1 to 9 in Mediterranean specirnens. Male ernbryos and fully developed fetuses are more nurnerous than fernales. Among the free-living specimens, nurnber of males and fernales is practically the same. The cornrnon torpedos from the coast of Senegal are larger and the eggs are heavier than Mediterranean specirnens. Key words: Pisces, Torpedinidae, Torpedo torpedo, Reproductive biology, Senegal, Eastern Tropical Atlantic.Among the five species of genus Torpedo recorded from the coast of Senegal, the common torpedo, Torpedo torpedo is that most cornrnonly caught in the area. Adult males and fernales studied were over 300 mm and 310 mm total length (TL), respectively, with the largest male and the largest female recorded being 445 mm and 550 mm TL respectively. Size at birth was between 102 and 125 mm TL (mean 112.12 mm; s.e.m. 5.58). Weight of eggs ranged frorn 6.2 to 8.0 g (rnean: 7.07; s.e.m. 0.5). Gestation lasts longer, from 6 to 8 rnonths, than in the Mediterranean specimens. A calculated chernical balance of development based on rnean dry weights of the fully developed fetuses and ripe oocytes was 1.58 for T. torpedo. This value shows that this torpedinid is not a pure lecithotrophic species, and the role of the rnother during gestation is not negligible. The fecundity (s.1.) of T. torpedo ranges from 5 to 28 in Senegalese specimens as cornpared to 1 to 9 in Mediterranean specirnens. Male ernbryos and fully developed fetuses are more nurnerous than fernales. Among the free-living specimens, nurnber of males and fernales is practically the same. The cornrnon torpedos from the coast of Senegal are larger and the eggs are heavier than Mediterranean specirnens. Key words: Pisces, Torpedinidae, Torpedo torpedo, Reproductive biology, Senegal, Eastern Tropical Atlantic.Among the five species of genus Torpedo recorded from the coast of Senegal, the common torpedo, Torpedo torpedo is that most cornrnonly caught in the area. Adult males and fernales studied were over 300 mm and 310 mm total length (TL), respectively, with the largest male and the largest female recorded being 445 mm and 550 mm TL respectively. Size at birth was between 102 and 125 mm TL (mean 112.12 mm; s.e.m. 5.58). Weight of eggs ranged frorn 6.2 to 8.0 g (rnean: 7.07; s.e.m. 0.5). Gestation lasts longer, from 6 to 8 rnonths, than in the Mediterranean specimens. A calculated chernical balance of development based on rnean dry weights of the fully developed fetuses and ripe oocytes was 1.58 for T. torpedo. This value shows that this torpedinid is not a pure lecithotrophic species, and the role of the rnother during gestation is not negligible. The fecundity (s.1.) of T. torpedo ranges from 5 to 28 in Senegalese specimens as cornpared to 1 to 9 in Mediterranean specirnens. Male ernbryos and fully developed fetuses are more nurnerous than fernales. Among the free-living specimens, nurnber of males and fernales is practically the same. The cornrnon torpedos from the coast of Senegal are larger and the eggs are heavier than Mediterranean specirnens. Key words: Pisces, Torpedinidae, Torpedo torpedo, Reproductive biology, Senegal, Eastern Tropical Atlantic

Model Continuity in Discrete Event Simulation: A Framework for Model-Driven Development of Simulation Models.

Most of the well known modeling and simulation methodologies state the importance of conceptual modeling in simulation studies and they suggest the use of conceptual models during the simulation model development process. However, only a limited number of methodologies refers to howto move from a conceptual model to an executable simulation model. Besides, existing modeling and simulation methodologies do not typically provide a formal method for model transformations between the models in different stages of the development process. Hence, in the current M&S practice, model continuity is usually not fulfilled. In this article, a model driven development framework for modeling and simulation is in order to bridge the gap between different stages of a simulation study and to obtain model continuity. The applicability of the framework is illustrated with a prototype modeling environment and a case study in the discrete event simulation domain

Effects of Coulomb interactions on the splitting of luminescence lines

We study the splitting between the right-hand and left-hand circularly polarized luminescence lines in a quantum dot under relatively weak confinement regime and resonant high-power excitation. When the dot is populated with an even number of electron-hole pairs (biexciton and higher excitations), the splitting measures basically the Zeeman energy. However, in the odd number of pairs case, we have, in addition to the Zeeman and Overhauser shifts, a contribution to the splitting coming from Coulomb interactions. This contribution is of the order of a few meV, and shows distinct signatures of shell-filling in the quantum dot.Comment: Submitted for publicatio